Framing Lumber Calculator — Linear Metres & Board Count
Calculate linear metres of timber for any framing project — wall plates, rafters, battens, joists and noggins. Enter lengths, quantities and cross-sections to get a full cut list with total linear metres and estimated weight.
How the framing lumber calculator works
- 1Enter each timber type with cross-section (e.g. 48×98 mm), quantity and individual length
- 2Linear metres per line item: quantity × length
- 3Total linear metres: sum of all line items
- 4Weight: cross-section area (m²) × length (m) × timber density (typically 500 kg/m³ for softwood)
- 5Add 10–15% waste for cuts, splits and selection
- 6Timber is sold by the running metre — round up each line item independently
Worked example
Roof structure: 12 rafters at 4.2 m, 6 ridge board pieces at 2.4 m, 24 noggins at 0.6 m. All 48×98 mm C24 timber.
Rafters: 50.4 lm. Ridge: 14.4 lm. Noggins: 14.4 lm. Total: 79.2 lm. With 10% waste: 87.2 lm. Estimated weight: 207 kg.
Frequently asked questions
What is a linear metre of timber?
A linear metre (lm) is simply one metre of length, regardless of cross-section. Timber merchants sell by the running metre — the price varies by cross-section and species.
What timber size should I use for rafters?
Rafter size depends on span and spacing. For a 3 m rafter span at 600 mm centres in C24 softwood, 47×150 mm is typically sufficient. Always consult span tables or a structural engineer for roof design.
What is C16 vs C24 timber?
C16 and C24 are strength grades for softwood. C24 is stronger and stiffer — required for most structural applications (rafters, joists, studs in load-bearing walls). C16 is acceptable for non-structural use.
How much does a linear metre of 47×100 mm timber weigh?
At 500 kg/m³ average density: 47×100 mm = 0.0047 m² cross-section. Per metre: 0.0047 × 500 = 2.35 kg/lm. A 4.2 m rafter weighs approximately 9.9 kg.
What is the difference between sawn and planed timber?
Sawn (regularised) timber has rough surfaces and is slightly oversized — 47×100 mm sawn gives approximately 45×97 mm actual. Planed timber (PAR/CLS) has smooth surfaces and is smaller — always check actual dimensions.